Technical Abstract:
Flavobacterium columnare is an aquatic bacterium that is highly infectious in warm and cold water fish. In the channel catfish (Ictalurus punctatus) industry it causes columnaris disease and has a negative impact on production (~$30 million/year). We developed a modified F. columnare isolate by passage on an antibiotic (rifampicin). Changes in the lipopolysaccharide (LPS) profile were shown by immunoblots that revealed the higher molecular weight bands of LPS were absent in the rifampicin modified isolate. Anti-sera generated in channel catfish from the vaccine isolate (genomovar I) or from a genomovar II isolate (ALG-530) cross reacted in immunoblots with the LPS and immunodominant proteins of either type I or type II isolates suggesting that the core antigens are conserved. In vivo reversion to virulence studies demonstrated the vaccine to be safe at ten times the normal vaccine dose in 10 day post hatch (DPH) channel catfish fry. Efficacy of the vaccine was demonstrated in 10 and 48 DPH channel catfish [Relative percent survival (RPS) from 71-94%]. Vaccine efficacy has also been demonstrated in eyed channel catfish eggs immunized 24 to 48 hours prior to hatching. RPS ranged from 50-77 % following challenge at greater than 100 days post vaccination. Recent laboratory and field studies demonstrated the application of this vaccine in largemouth bass (Micropterous salmoides) an important sportfish in the US and thus, the vaccine may have application in numerous other fish.